Correct backfill material
· The best approach is 3/4 clean gravel up to the sub base. It is self compacting just need to run a plate over it at the end. I use sdr35 perforated pipe on top of the collar pitched to daylight if possible otherwise to a sump standpipe of 10 or 12 inch PVC. I also wrap the overdig in filter fabric and them over the clean stone.